Inaccurate mentalised threats are constructed in the brain for very good reason. Typically they are real when they form, and are required in order to stabilise the caregiving environment when young. (If mum/dad gets very angry when I make a fuss trying to get what I want, I quickly develop a fear of standing up for myself. This fear is useful to placate mum/dad, but not useful when I'm an adult and getting walked over.)
Strangely, the brain seems to have its own method to explain to the owner what these inaccurate mentalised threats are - dreams. And I can assure the author that the cure to nightmares is not as simple as recognising they are not real - there is a cure to them though. Dreams were extremely important to my own development/de-anxious-ing, so I wrote a paper on this function during my Msc in Psychology. It is free to download here: https://psyarxiv.com/k6trz, and was discussed on HN here: https://news.ycombinator.com/item?id=19143590